Sucrase-isomaltase is present in the surface of your small intestine and is responsible for one of the steps in breaking down sugars in foods. Mutations in the gene can cause sucrose intolerance. SI is relatively young – only conserved among placental mammals, perhaps reflecting a recent change in diet. The sucrase and isomaltase parts of the enzyme are so similar that they may have resulted from a gene duplication.
Click here to see all 8621546 letters of Day 78 with SI underlined.